Ok, so up until a few weeks ago I was running a 3.3" pulley on my MP112 and making 8 lbs. of boost and everyhing was great. I decided to do a cam swap and went with a 220/226 xer lobes on a 114 lsa. Finished the cam swap and lost 3 lbs. of boost. Went to the track last Friday and went 13.70 @ 99. Before the cam and SC3000 cnverter I went 13.62 @ 99. So I actually went a little slower with the new cam on less boost. So yesterday I decided to pulley farther down to a 3.1" and get my boost back to where I was before the cam swap. STILL ONLY SHOW 5 lbs! What the hell is going on????? I can understand losing some boost with the cam swap whether it be from too much overlap or flowing more air or whatever, but adding a smaller pulley and still not gaining boost back! I am so confused............. Any help is appreciated.

 

belt slip or your crank spinning?

 

Crank is pinned! Belt slip, maybe........... I am using a 112" belt. The boost does not jump up and down like a slip would. It holds strong a 5.

 

Not trying to ask a dumb question, but has it been re-tuned with the new cam?

 

what valve springs are you using and whats the lift on the cam?

 

I think you'll have to pulley down a bit more to see 8psi with that cam. I needed a 2.8" pulley on a similar rig with 220/220 .581 115LSA cam to see 8+ psi.

 

I also put on the 2.8" pulley for the bigger boost. (8+).Another question, did you change springs and pushrods when you swapped the cam? #7

 

Cam is .581/.585 lift. I use the patriot gold dual springs. And, yes I did have it retuned after the cam.

 

sounds like you shouldve bought a Whipple.....